Apparatus for controlling refrigerant flow in a refrigeration machine



NOV. 22, 1966 w CLARK ET AL 3,286,482

APPARATUS FOR CONTROLLING REFRIGERAN'I FLOW IN A REFRIGERATION MACHINE Filed July 10, 1964 0 o o 32 0 0 0 0 0 0 0 o o /|2 o o o o o 023 o o 000 0000000 5 M o o o o o o o o o oo o o o o 20 I6 3 (pressure diffe -ence) surge I9 36 35 l8 4 I 24 T o o o o o o o o o o o o I? 2 020 00000 0000 0 0 0 0 o S8; LOAD o o o o 0 0 o y (refngerant flow rate) 0000 0 000000000 43 A oooooooooooooooo 4o INVENTORS.

WILLIAM E. CLARK. 3B CARL M. ANDERSON.

WILLIAM L. MC GRATH. 5: W

ATTORNEY.

United States Patent APPARATUS FOR CONTROLLING REFRIGERANT FLOW IN A REFRIGERATION MACHINE William E. Clark, Carl M. Anderson, and William L.

McGrath, Syracuse, N.Y., assignors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed July 10, 1964, Ser. No. 381,650 4 Claims. (Cl. 62218) This invention relates broadly to refrigeration apparatus. More particularly, this invention relates to the control of refrigerant flow in a refrigeration machine of the kind used to provide chilled water for use in air conditioning installations.

In refrigeration machines having a relatively high tonnage requirement, there is provided a compressor arranged so as to extract gaseous refrigerant from an evaporator and forward it to a condenser where the refrigerant is liquefied. The refrigerant flows from the condenser through a refrigerant metering means to the evaporator where it is converted to the gaseous phase as it extracts heat from a circulating medium used to cool air flowing within an enclosure served by the machine. In the condenser, high pressure gaseous refrigerant at elevated temperatures is converted to liquid refrigerant through heat transfer with a medium flowing within the condenser having a temperature lower than the gaseous refrigerant. In communication with the condenser there is normally provided a receiver for collecting liquid refrigerant formed in the condenser prior to its passage to the evaporator. The receiver usually contains refrigerant both in the liquid and gaseous phases and flow from the receiver is regulated by a float operated valve mechanism.

In a refrigerant flow control device of the kind de scribed the level of liquid refrigerant collected in the receiver is a function of the pressure difference between the high pressure side of the machine and the low pressure side of the machine and the load on the machine, it being understood the condenser is disposed in the high pressure side and the evaporator in the low pressure side of the machine. Refrigerant flow from the condenser to the evaporator occurs in an amount related to the loading on the machine and automatic controls such as suction guide vanes are provided for the purpose of maintaining flow rates corresponding to machine loading. Float operated valve assemblies are designed to pass a predetermined amount of refrigerant in accordance with the level of liquid refrigerant collected. The float operated valve assemblies contain moving parts which are subject to fouling 'and which may be damaged when the machine is transported from its place of manufacture to the location of its use.

The chief object of this invention is the provision of an improved refrigerant flow control means for passing refrigerant in both the liquid and gaseous phase which is not only more economical tofabricate than the conventional mechanism employed for this purpose, but is also capable of passing the liquid refrigerant to the evaporator in a manner as to assure smooth, turbulence-free efficient flow.

It is an additional object of this invention to provide a refrigerant flow control means in which the flow control means is provided with mechanism permitting an increase in the flow of refrigerant under certain operating conditions when it is desirable that such increased flow be made available to the evaporator.

A further object of the invention is the provision of an improved method of controlling refrigerant flow in a refrigeration machine wherein losses due to the passage of liquid and refrigerant through a common opening are maintained at a minimum.

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Another object of the invention is the provision of a refrigerant flow control device for passing liquid and gaseous refrigerant wherein uniform agitation of refrigerant under certain operating conditions is achieved.

These objects are attained with a refrigerant flow control member for regulating passage of refrigerant from the high pressure side of a refrigeration machine to the low pressure side of a refrigeration machine comprising a hollow upright member provided with a plurality of -vertically spaced openings communicating with the various levels of liquid refrigerant under a variety of operating conditions in such a manner that either gaseous or liquid refrigerant, or a combination of both, may be efficiently passed to the evaporator. I

Other objects and features of the invention will be apparent upon a consideration of the ensuing specification and drawings in which:

FIGURE 1 is a perspective view of a portion of a refrigeration machine, having certain parts broken away in the interest of clarity, incorporating a preferred embodiment of the refrigerant flow control means forming the invention;

FIGURE 2 is an end view, partly in section, of the machine shown in FIGURE 1 with the refrigerant compressor illustrated diagrammatically;

FIGURE 3 is a perspective view illustrating an additional modification of a refrigerant flow control contemplated by this invention;

FIGURE 4 is an elevation view, partly in section illustrating a further modification of the refrigerant flow control member; and

FIGURE 5 is a chart illustrating the operation of a centrifugal compressor over a given operating range.

Referring more particularly to the drawings, there is shown a centrifugal refrigeration machine 10 of the kind employed for the purpose of cooling a relatively large quantity of water for passage to an enclosure served by the apparatus. The centrifugal machine 10 includes a shell 12 housing the heat transfer units associated with the machine. In the shell 12 there is provided a partition 14 separating the interior of the shell into a high pressure condenser compartment 16 and a low pressure evaporator compartment 18. In addition, there is shown structure defining a refrigerant chamber 20 having communication with both the condenser and evaporator compartments.

,In the condenser compartment 16 there is provided a condenser tube bundle 22 of conventional design supported by a plurality of tube sheets 23 connected to the partition and the outer surface of the shell as illustrated. In the evaporator compartment 18 there is provided an evaporator tube bundle 24 likewise of conventional design. Suction line 26 connects the evaporator compartment 18 with the inlet of the compressor 28 and discharge line 30 connects the outlet of the compressor 28 with the condenser compartment 16.

Disposed within condenser compartment 16 is a baffle 32 aligned with the connection between the discharge line 30 and the shell 12 for the purpose of protecting the condenser tube bundle by receiving the impact of the gaseous refrigerant delivered to the condenser compartment under relatively high pressure. The condenser baflle 32 is supported by a plurality of struts 34, one such strut being illustrate-d in FIG. 2.

Disposed within the refrigerant chamber 20 is a re frigerant flow control device 36, illustrated in FIGURES 1 and 2, forming the subject of this invention. The refrigerant flow control device regulates passage of refrigerant from the chamber 20 to the evaporator compartment inlet 38 through a passage 40. The refrigerant flow control device comprises a hollow tubular member 44 which may be defined as a standpipe, having a top cover 45. Oriented about the periphery of the standpipe 44 are a plurality of openings 46, as shown in FIGURE 2. These openings are spaced throughout the height of the standpipe and preferably define a spiral or helical path or at least a portion thereof. The standpipe is arranged so that the interior communicates with chamber outlet 48 communicating in turn with the refrigerant flow passage 40.

A second embodiment of the invention is illustrated in FIGURE 3 wherein the hollow standpipe 44 is formed by a plurality of individually nested tubes 47 of varying hei t.

12 FIGURE 4 there is illustrated an additional embodiment of the invention wherein the refrigerant flow control device 36' includes a pressure responsive valve assembly 50 comprising an interior cylindrical wall 52, depending from the top cover 45', in communication with opening 51 disposed therein. In addition, wall 52 is provided with openings 54 disposed therein and an opening 61 in the lower end thereof. There is arranged in the cylindrical wall a movable piston member 56, having side openings 58 which, as will be later explained, com municate with the openings 54 in the cylindrical wall 52. Piston 56 is urged upwardly against a snap ring disposed in cover 45 as in FIGURE 3 by a spring member 60. The interior of the cylindrical wall is exposed to the section of the chamber 20 which accommodates gaseous refrigerant under normal operating conditions.

Considering the operation of the invention, reference may be had to FIGURE showing a series of curves representing operation of a single stage centrifugal compressor, equipped with suction guide vanes, employed in a centrifugal refrigeration machine, at different capacities. The graph depicted in FIGURE 5 illustrates the relationship between the loading on the machine compared to the lift or pressure difference or pressure ratio developed by the impeller.

The embodiments described are effective to pass refrigerant to the evaporator within the operating range of the machine. It will be appreciated that within the operating range of the machine certain operating conditions will cause the level of the liquid refrigerant to rise within the chamber. For example, a sudden drop in the temperature of the condensing cooling at a particular machine loading will cause liquid refrigerant to collect in the receiver. Each of the embodiments of the invention disclosed herein is effective to increase passage of liquid refrigerant to the evaporator under these circumstances.

The embodiments illustrated in FIGURES 1, 2 and 3 are dimensioned so that at design conditions the level of liquid refrigerant will be intermediate the height of the standpipe or collection of tubes as the case may be. A rise in the level of liquid refrigerant will cause additional openings 46 or additional tubes to pass liquid refrigerant and thus maintain acceptable refrigerant flow rates. On the other hand, should the level of liquid refrigerant fall less openings 46 will pass liquid refrigerant. It will be understood that gaseous refrigerant collected in receiver 20 will pass through these openings above the liquid level. With this arrangement only one opening 46 or tube top can pass both liquid and gaseous refrigerant.

The embodiment illustrated in FIGURE 4 is automatically effective in response to a predetermined difference in the pressure between the high side and low side of the machine to provide additional passage of refrigerant to the evaporator. It will be observed that the refrigerant flow control device 36 includes a valve assembly 50 disposed therein. The piston member 56 is urged by spring 60 to a position within cylinder 52 such that openings 58 in piston 56 are in registry with openings 54 in the cylinder in the absence of a pressure difference across the valve in excess of the force exerted by the spring. The interior of piston 56 communicates through opening 51 with the high pressure side of the system. The surface of piston 56 engaged by spring 60 communicates with the evaporator through Opening 61 disposed in cylinder 52. When the difference in pressure between the condenser and the evaporator exceeds a predetermined value, sufficient to overcome the spring action, the piston is moved downwardly so that openings 54 and 58 are out of registry. The movement of the piston is usually gradual so that a modulating effect is obtained. Should the compressor be operating in a part of the range, such as low load, and the pressure difference or lift drops then gaseous refrigerant may pass through openings 54 and 58. The amount of gaseous refrigerant is not large enough to affect the performance of the machine. Should the compressor be operating in a part of the operating range where liquid refrigerant in the receiver is rising as would be caused by the pressure difference decreasing then liquid refrigerant will pass through openings 54 and 58.

A particular advantage has been observed when the construction illustrated in FIGURE 3 has been employed. The liquid refrigerant entering any given tube 47 flashes and chokes the flow through the particular tube resulting in an action similar to that encountered in passing through orifices disposed in series relation.

While we have described a preferred embodiment of the invention, it will be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. In a refrigeration machine including an evaporator, a compressor, a condenser connected to form a refrigerant flow circuit wherein chamber means is interposed between the condenser and evaporator for collecting both gaseous and liquid refrigerant from the condenser for passage to the evaporator, refrigerant flow control means disposed in said chamber means, said control means comprising a hollow passage means disposed in said chamber the interior being in communication with the evaporator, said passage means having vertically spaced openings formed therein for passing refrigerant to the evaporator, said openings passing either liquid or gaseous refrigerant depending upon the level of liquid refrigerant present in the chamber.

2. Refrigerant flow control means as described in claim 1 wherein said openings are vertically spaced apertures extending through said hollow passage means to provide communication between the space defined by the chamber and the interior of the member.

3. Refrigerant flow control means as described in claim 1 wherein said hollow member includes a plurality of individual tubular elements, each having a different height.

4. Refrigerant control means as described in claim 2 including valve means controlling refrigerant flow through at least one of said openings, said valve means being responsive to a predetermined difference between evaporator and condenser pressure.

References Cited by the Examiner UNITED STATES PATENTS 920,392 5/ 1909 Rider 62222 2,182,664 12/1939 GoWans 62-525 2,237,239 4/ 1941 Smith 62525 X 2,791,105 5/1957 Aronson 62511 X MEYER PERLIN, Primary Examiner. 

1. IN A REFRIGERATION MACHINE INCLUDING AN EVAPORATOR, A COMPRESSOR, A CONDENSER CONNECTED TO FORM A REFRIGERANT FLOW CIRCUIT WHEREIN CHAMBER MEANS IS INTERPOSED BETWEEN THE CONDENSER AND EVAPORATOR FOR COLLECTING BOTH GASEOUS AND LIQUID REFRIGERANT FROM THE CONDENSER FOR PASSAGE TO THE EVAPORATOR, REFRIGERANT FLOW CONTROL MEANS DISPOSED IN SAID CHAMBER MEANS, SAID CONTROL MEANS COMPRISING A HOLLOW PASSAGE MEANS DISPOSED IN SAID CHAMBER THE INTERIOR BEING IN COMMUNICATION WITH THE EVAPORATOR, SAID PASSAGE MEANS HAVING VERTICALLY SPACED OPENINGS FORMED THEREIN FOR PASSING REFRIGERANT TO THE EVAPORATOR, SAID OPENINGS PASSING EITHER LIQUID OR GASEOUS REFRIGERANT DEPENDING UPON THE LEVEL OF LIQUID REFRIGERANT PRESENT IN THE CHAMBER. 